Back to the topic's orginal idea (No, not the porn part), screaming when striking has been since long in many oriental martial arts used. Apparently the strength liberated with each hit is higher, and the hit is much harder.
I can't say if that is correct or not, as I myself have been trained in amateur boxing and we never did scream at all when striking -though I assure you
it did hurt a lot when you landed a good blow-
May be their couch thought the technique could be well translated to tennis, in order to have harder strikes. Probably Skybird can tell something more about this, as he is more versated in oriental martial arts
